Trying to put a KAC RAS rail on my BCM M4 14.5” socom upper and it is not going on. Took me a few minutes with my LE6920. What gives? Using the delta ring tool doesn’t help. The base of the rail won’t slide all the way onto the barrel nut.
The KAC RAS has a clamp that has to fit over the barrel nut that, when tightened down, holds the handguards in place. You’ll need to open it up a bit more, then carefully maneuver everything into place.
Finally got it. Thanks. The trick is to keep the gun horizontal and not vertical like I was doing so the clip above the gas tube slides under the barrel nut. What a pain.
You’re welcome. The first time I installed one, KAC RAS and I went 10 rounds in the ring before I finally figured it out.
Does that rail free float or semi free float the barrel? What’s the point that part of the design? I never messed with the one of my issued rifle because I didn’t feel like losing any parts in a place where I could not get replacement parts.
The KAC RAS (or RIS?) that I’m thinking of, is a drop in quad rail handguard. They use a clip that is tightened against the inside of the barrel nut with a screwdriver to lock the handguard in place. It doesn’t free float the barrel, it simply locks the handguards in place. I believe this is so the POA of any lasers mounted to the handguards will be consistent.
Tagged for interest - I need to install a RAS on a BCM C8 clone upper but the rail hasn’t arrived yet.
A similar design that actually free floats is the DD OMEGA rail if your interested in a free floating quad rail.